This invention relates to a process for the production of conjugated diolefins having 4-6 carbon atoms. More particularly, this invention relates to a process for the production of conjugated diolefins having 4-6 carbon atoms from the corresponding monoolefins by a vapor phase reaction conducted at a high temperature in the presence of oxygen wherein a specific catalyst is used to obtain the end product in a high yield.
A process for the vapor phase dehydrogenation of monoolefins conducted at a high temperature in the presence of oxygen while allowing the oxygen to participate in the reaction is already known as a means for producing diolefins. This process is known as the so-called "oxidative dehydrogenation process" and is characterized in that it is advantageous with respect to the thermal energy of the reaction as compared with the direct dehydrogenation process wherein monoolefins are heated in the absence of oxygen with a heating medium such as steam. However, such oxidative dehydrogenation is an oxidation reaction and as such, has disadvantages in that it permits the formation of a number of by-products and fails to produce the desired diolefins in a high yield.
DISADVANTAGES, GENERAL, THE OXIDATIVE DEHYDROGENATION REACTION IS CARRIED OUT IN THE PRESENCE OF A CATALYST TO OVERCOME THE AFOREMENTIONED DISADVANTAGES OR IN OTHER WORDS, TO ENHANCE THE REACTION RATE AND THE YIELD OF THE PRODUCT. Examples of catalysts proposed for said oxidation dehydrogenation include a catalyst comprising oxides of tungsten and cobalt or oxides of molybdenum and cobalt (Japanese Patent Publn. No. 27049/1965), a catalyst comprising oxides of molybdenum, bismuth and arsenic (British Patent 906,215) and a catalyst comprising oxides of (i) tellurium and (ii) iron, tin or titanium (Japanese Patent Publn. No. 5723/1968). However, all of these hitherto proposed catalysts are not satisfactory in their activity and selectivity so that the yield of conjugated diolefins achieved is not high. Thus, there is still a great demand for development of a new type catalyst which can overcome these disadvantages found in the conventional catalysts.